If your hookup buddy or boyfriend reaches for a condom without being asked, then he may have high testosterone levels. Whereas a guy who needs to be convinced to use protection and gives you a hard time about it might be lacking in the testosterone department. (Testosterone is associated with boldness and confidence. While low levels of it, in case you weren't paying attention in high school bio class, can sometimes lead to a dude being tired all the time and it might also signify fertility issues.)

The hormone is also associated with risk-taking behavior, which is why the researchers at the University of Michigan were slightly surprised at the results. But they concluded that for college-aged men, asking to use a condom is actually considered a risk (because it might lead to not having sex). And they view that as riskier than not using a condom at all. "The 'social risk' of insisting on using a condom might require more boldness and confidence than having unprotected sex," explained one of the researchers to LiveScience.com.

Ummm. Really, college boys? We're kinda concerned that you don't understand the true risks of have sex sans protection. On the other hand, we think this study has just given women a genius way to convince guys to wear condoms 100 percent of the time. Just tell him that research has found manly men have absolutely no problem rolling on the rubber, whereas men who are neither bold nor confident (and just might have baby-making problems) resist condoms. We can't imagine him trying to weasel his way out of safe sex after hearing that! (It's like the scientifically-backed version of "All the cool kids are doing it.)